Rheostat.



1 U6 84 w CROSS REFERENCE EXAMINER A. I. GRABHAM."

BHEOSTAT.

APPLIOATIOI FILED HOV. 8, 1912. 1,093,718, P Patented June 2, 1914 1 d I: E 1. j, 53

positions for employment in apparatus a the current has to passin order to give a resired.

. is employed may be of any suitable kind ac- .composition, and Figure 1 of which is a seci-sFlanganese oxid a 2 drams.

UNITED STATES PATENT OFFICE.

ARTHUR ILLINGWOBTH GRABH'AM, OF WELLINGTON, NEW ZEALAND.

BHEO

1,098,718. Specification of To all whom it may concern:

Be it known that I, AnTnTm ILLING- whereby the amount of current flowmg to electrical lighting, heating or power devices maybe regulated and controlled.

The object of the invention is to produce a solid medium or resistance through which sistance to the voltage and amperage varying directly according to the distancethrough which the current passes.

By means of the invention the current of electricity may be gradually reduced from the maximum to a minimum or increased from a minimum to a maximum either by steps or by sliding contact 'as. may be de- The rheostat with which the composition cording as to whether the medium is nsed for controlling lighting, heating or power purposes.

A suitable rheostat for controlling current for electric lighting is shown in the drawing in order to illustrate the use of the tional elevation; Fig. 2 is a sectional plan, and Fig. 3 is a plan view of the rheostat.

The ingredients of which the block is composed comprise generally n nganese oxid zinc oxid, silicate of soda, and br s filings in suitable propdftioiis the who e bemg mixed together and molded into blocks or, rods or into other suitable forms accord ing to the shape that is required audiesired baked so as to obtain the requlre hardness? I have found the following proportions suitable for a switch for a 100 volt circuit: manganese oxid, two drams, ine oxid, two drams, silicate of soda of the 'viscous kind, one hundred and brass filings from two and three quarters to three and one half drams.

STAT.

Letter l' ten Patented June 2, 1914.

100 minims. Brass filings 2% to 3% drams.

The viscous silicateflof soda forms the blndlng agent ut 1 t e so 1 silicate of Be added.

In the rheostat shown in the drawings a block 1 of semicircular or circular form is sired shape formed throughout its upper surface. Along this contacting way a contacting piece 3 is. adapted to contact and may comprise a roller pivoted in a bracket '4 fixed upon a sleeve 5 journaled upon a spindle 6 fixed in the base 7. The sleeve 5 passes through a covering casing 8 which may be screwed or otherwise fixed to the base 7 while a coil spring 9 located upon the sleeve 6 in compression between the bracket 4 and the covering casing 8 gives the required tension to the contact piece 3 upon the contacting way 2. One lead wire 10 of the circuit is connected to a binding post 11 fixed in the base 7 while one end of the block 1 is provided with a metal portion 12 which also passes into the post and is retainedby the screw 13 in order to make a good electrical connection with the block 1. The wire 14 which leads to the electrical device is' connected to a binding post 15 also fixed in the base 7 and secured by nuts 16. A wire -17 makes electricalconnection with the binding post 15 and the spindle 6.

The block 1 is mounted upon an asbestos slate plate 18 fixed upon the spindle 6 by nuts 19 and spaced a suitable distance from the base 7 in order to prevent undue heating of the base.

A handle 20 is fixed upon operating the contacting piece 3. In F g; 3 the handle portion 20 is fixed to the brac et 4 while the slot 21 is provided for the handle to travel in. A stop 22 at one end of the piece 3 in that direction, this stop is not in contact with the block I so that when the rent will flow through the block.

When it is desired to obtain the varying degrees of light, heat or power as the case may be, the handle 20 is operated so as to cause the roller 3 to contact with a difi'erent art of the block, and when the contact 3 IS incontact with the stop 22 at the end of soda is used a slight quantity oI-waEr must the sleeve 5 forblock limits the movement of the contacting contacting piece 3 is resting upon it no cur- Application filed November s,ia12. Scria1No.730,210. 1S 2 L; O

Silicate of soda (of the viscous employed having a contacting way 2 of dethe block remote from the binding post 11 the current is then cut oil and when it is in contact with the metal binding post 11 at the other end of the block the full glow of the current'will pass through the circuit. When the contact 3 is in contact with the end of the block remote from the binding post 11 the minimum amount of current will flow to the electrical device as the case may be. By adjusting the contacting piece to different positions between the minimum and the maximum the desired amount of current is caused to pass to the electrical device.

I claim:

-1. In a rheostat a resistance block consisting of manganese oxid, zinc oxid, silicate of soda, and brass filings mixed together in suitable proportions.

2. In a rheostat a resistance block consisting of manganese oxid two (2) drams, zinc oxid (two) 2 drams, silicate of soda, one hundred (100) mim'ms and brass filings, two and three-quarters (2%) to three and one- 7 half (3%) drams.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

ARTHUR ILLINGWORTH GRABHAM.

Witnesses:

ROBERT I'IEN'RY MODLIN, PERCY WAILACE SAMPSON. 

